Higher frequencies of traffic noise prove most annoying

Many of the most prevalent frequencies in traffic noise signals overall are toward the lower end of the audible spectrum, for example the deep bass rumbles of many engines and exhausts.

But newly published research indicates that it is high frequencies – such as the hiss of tyres on wet roads in the rain, for example – that cause the greatest amount of annoyance for those forced to overhear them.

A paper published at the 2nd UNTREF International Congress on Acoustics looked at real-world recordings of road noise obtained in Buenos Aires, Argentina, and asked a relatively small sample of people to rate them according to how annoying they were.

The researchers found that higher frequencies of traffic noise are the most annoying overall, which tallies with earlier studies cited in their introduction.

In related studies, researchers found that even indoors – where low-frequency rumbles are more likely to persist than higher frequencies shut out by the building envelope – it is still the higher frequencies that cause the most annoyance.

For vehicle manufacturers, the conclusions are an important reminder that vehicle noise insulation should not only tackle the lower frequencies – although these are generally more pervasive of surrounding buildings – but should aim to shut out high frequencies too to minimise annoyance for passers-by and nearby residents.